This invention relates to a new and improved system and process for the enhancement of mechanical pulp wood fibers having application to the production, processing and adaptation of mechanical pulp to a form providing a product eminently suited to the making of quality newsprint and groundwood specialties. It provides an answer to a number of problems which have existed for a considerable number of years. These problems derive from the fact that pursuant to the existing prior art it is deemed essential to add a substantial quantity of expensive chemical pulp to a given amount of mechanical pulp in order to achieve a resultant pulp which is satisfactory for the production of newsprint or groundwood specialties such as supercalendered or light weight coated paper. Not only is the chemical pulp expensive and increasing in cost but the very nature of it is such that the chemicals thereof tend to adversely affect desirable properties of the mechanical pulp with which it must be combined. Furthermore the addition of chemical pulp has been found to inherently limit the optical and printing properties of those paper products to which the combined pulp is applied. Another important adverse factor is that the chemical pulp is a low yield pulp. This last evidences both a resource and an environmental problem since our supply of trees and has become seriously depleted.
The most pertinent of the previous efforts to solve the noted problems produced a suggestion that they may be alleviated by a single stage sulfonation of mechanical pulp, namely by spraying it with a suitable chemical in the course of its conventional processing. However the cost of the chemicals for such purpose has proven to be very high and the results thereof unsatisfactory.
As will be seen from the following disclosure, the present invention deals with and affords a highly satisfactory solution to the foregoing problems and at the same time makes a significant contribution to the art in several respects.
A basic feature of the embodiments and practice of this invention is a two stage sulfonation system and process which can be applied to the enhancement of mechanical pulp in a number of ways and in reference to a number of different types of such pulp, in the process of which to save a significant amount of chemical and its cost, to reduce energy requirements in the application of the resultant pulp to the production of newsprint, groundwood specialty papers and the like and to provide a quality of the mechanical pulp obviating need for addition thereto of chemical pulp as practiced in the prior art.
The foregoing references to the prior art exhibit the extent of background knowledge of which those substantively involved in the preparation of this disclosure are aware. They know of no prior art specifically pertinent to the points of novelty herein set forth as forming part of the present invention.